#pragma once
#include <stdio.h>
#include <stdlib.h>
#define MAX 255+1
int ceshi(char *str)
{
	int arr[MAX];
	for (int i = 0; i < MAX; i++)
		arr[i] = 0;
	while (*str != '\0'){
		int index = *str;
		arr[index]++;
		str++;
	}
	int flag = 0;
	for (int i = 0; i < MAX; i++){
		if (arr[i] == 1){
			return i;
		}
	}
	return -1;
}
void testString()
{
	char str[MAX];
	scanf("%s", str);
	char c = ceshi(str);
	if (c != -1)
		printf("%c\n", c);
	else
		printf("-1\n");
}